Device for fire protection in electrical systems

ABSTRACT

An apparatus ( 30, 50, 60 ) for protection against fire in an electrical system ( 10 ) at connection points for electrical cables ( 510 ) comprises at least one thermal element ( 50 ) which is operable to register and warn in response to increased temperature in the electrical cables ( 510 ) or in one or more electrical elements ( 30 ) whereat the cables ( 510 ) are coupled. A fire warning unit ( 60 ) is coupled in operation to the at least one thermal element ( 50 ) for sending a warning in an event that the thermal element ( 50 ) measures an increase in temperature above a temperature threshold. Use of the thermal element ( 60 ) makes in possible to detect early melting or fire.

FIELD OF INVENTION

The present invention concerns devices for protecting against fire inelectrical systems. Moreover, the invention relates to a method ofinstallation of fire protection devices in electrical systems,especially in relation to electrical system installers who installapparatus for fire protection for customers in return for remunerationfrom such customers. Furthermore, the present invention concerns amethod of using the device for detecting fires or risk of fire inelectrical systems. The invention is, for example, relevant in relationto connection points for electrical conductors and cables where poorelectrical contact can result in localized heat generation andsubsequently fire. Furthermore, the invention is concerned with aclamping means to fasten said protection device for electrical systems.

BACKGROUND OF THE INVENTION

It is well known that electrical systems give rise to fires infacilities and buildings. The reason is that a concentration in energyin the conductor network arise, and that electrical fuses for protectingagainst overload function first after insulation material has beendamaged, for example as a consequence of fire. Electrical fuse cupboardsand electrical fuse panels, or other types of connection cupboards suchas a data cupboard, are known electrical installations which can be anorigin for fire. Typical known causes to such fires are that a poorelectrical contact arises in connections which gives rise to localizedresistance points which result in warming in response to a flow ofcurrent through the points. Localized resistance can, for example, ariseover a longer period of time as a consequence of corrosion resultingfrom dampness or water. Such warming can result in damage to insulatorswhich can cause short circuits, electric arcs, overload and failure inelements of coupled electrical apparatus.

At points where two associated conductors are coupled together, problemscan arise as a consequence that metal ages and contracts, somethingwhich can results in heating of elements whereat the conductors arecoupled which thus a fire may arise.

A start of fire in such electrical fuse cabinets can have seriousconsequences. In addition to ruination of the fuse cabinets themselvesand corresponding material damage, interruption of electrical supply canalso result as a consequence. Such failures give rise to a significantproportion of fire damage in electrical facilities in industrialbuildings, private residences and other buildings as well asinstallations such as on ships, oil platforms, power station et cetera.Undesired development of heat in cables and fuses or other componentscoupled thereto in fuse cabinets can result in conductors welding,melting catching fire.

It is known that smoke alarms outside fuse cabinets are able to detectsuch events rather late, for example firstly after an actual fire hasarisen in the cabinet. To improve security, fire detectors can bemounted within the cabinet to provide an improved fire warning onaccount of generation of smoke being detected earlier; moreover, in thissituation, earlier detection of fire is unfortunately possible, butfirstly after heat generation has considerably progressed and gasses andsmoke have arisen within the cabinet, and finally possibly open flames.

In a published international PCT patent application no. WO2008/044939(Per Erik Lie, Norway), there is described a system for fire protectionin electrical installations. The system is operable to detect and hinderelectric fires in electrical distribution panels in private dwellings,wherein such electrical distribution panels comprise a fuse box and amain electrical distribution panel and a sub-electrical distributionpanel. A main switch couples the fuse box to the main electricaldistribution panel. First, second and third gas-. smoke- andheat-sensors are included in the system and are disposed in the fusebox, in the main electrical distribution panel and in the sub-electricaldistribution panels. A remotely-mounted main current breaker can beactivated for interrupting the current to the main electricaldistribution panel in a case of fire. The system is of benefit onaccount of changes can be implemented in the main electricaldistribution panel and the sub-electrical distribution panel, forexample changes involving including extra switches and/or fuses can beimplemented without a need to develop heat- or smoke alarm systemsfurther.

It is known to monitor temperature in cables by using thermocouples. Forexample, there is described in a published patent no. GB 1,280, 723 useof elements which change their resistance as a function of temperature.These elements can be used for measuring cable temperatures.

SUMMARY OF THE INVENTION

An object of the invention is to provide a fire warning apparatus forelectrical systems which is more effectively able to detect fire incables and similar, for example with regard the fuse cabinets, fusepanels and data panels.

A further object of the invention is to hinder occurrence of fires inelectrical systems at an early stage, for example beneficially beforefuses, conductors, switches and similar electrical elements begin toweld, melt or begin to burn and cause fires.

A further object of the invention is for early detection of faultconditions in connection boxes and fuse cabinets and thereby ensure thatelectrical elements are detached from the electrical power networkbefore a fire commences.

A further object of the invention is to be able to identify electricalelements in electrical cabinets which are faulty with a result that theydevelop warmth and can give rise to fire.

According to a first aspect of the present invention, there is provideda device as defined in the accompanying claim 1; there is provided anapparatus for fire warning in an electrical system including couplingpoints for cables, characterized in that the device includes at leastone thermal element which is operable to detect and warn regardingincreased heating in the electrical cables, one or more electricalelement whereat the cables are connected, and a fire protecting unitcoupled in use to said at least one thermal element for sending warningin an event that the thermal element measures a temperature increaseabove a temperature threshold.

The invention is of advantage in that the thermal element is moreeffective at detecting a danger of fire in the electrical system.

A major advantage of the invention is that advantageous disposition andmounting of the thermal element closely to points where electricalcables are coupled, which makes it possible to detect development ofwarmth at an earlier stage. Thereby, a risk of actual occurrence of fireis reduced.

The apparatus is beneficially implemented such that the thermal elementassumes a form of an elongate band which can be coupled in series alongconnection points for simultaneously monitoring a plurality ofconnection points. Optionally, the thermal element has a length in arange of 10 cm to 10 metres for example.

The apparatus is beneficially implemented such that the thermal elementis installed in a spatial region whereat the cables are coupled to theone or more electrical elements, for detecting warming in insulatingmaterial of the cables in a vicinity whereat the cables are coupled.Surprisingly to more effective to detect occurrence of fire by utilizingthe present invention in comparison solutions wherein the thermalelement is moulded into the housing for fuses and similar.

The device is beneficially implemented, such that the thermal elementcomprises at least two mutually different metals which in use induce anelectromotive potential when mutually joined, and which show a change inelectromotive potential when exposed to a temperature change when used.A thermistor implementation of the thermal element is also feasiblewithin the scope of the invention.

The device is beneficially implemented such that the thermal element isprovided with a sleeve or sock as outer protection, and wherein theaforesaid loop sock is adapted to provide an electrically-isolatingthermal contact with the aforesaid connection points in the electricalsystem.

The apparatus is beneficially implemented such that one or more clampingdevices are used to establish contact between the thermal element andthe cables, and wherein the one or more fastening devices press ormaintain the thermal element in the vicinity of (adjacent to) thecoupling points.

According to a second aspect of the invention, there is provided afastening device for coupling a thermal element of an apparatusaccording to the first aspect of the invention.

The fastening device is beneficially implemented such that the aforesaidfastening device includes a clamp for detachable clamping of the thermalelement to one or more of the connection points.

The fastening device is beneficially implemented such that the clamp isformed from two “L”-shaped clamp parts which are to an extent mutuallymoveable in a locked state and released free state, and thereby form twoclamp parts adapted to provide a clamping contact to one or morecoupling points. Moreover, the fastening device is implemented in suchthat the main part of the clamp part are coupled together via a lockingdevice adapted to provide the aforesaid locking position between theclamp parts.

The fastening device is beneficially slidable along the cables and atleast a part of the thermal element in order to clamp the thermalelement to the cables in a vicinity of the coupling points.

According to a third aspect of the present invention, there is providedan apparatus kit for making installation of the apparatus possiblepursuant to the first aspect of the invention.

Beneficially, the apparatus kit comprises one or more fastening devicesaccording to the second aspect of the invention.

A method of installing an apparatus according to the first aspect of theinvention is provided, wherein the method includes:

-   (a) laying a thermal element along coupling points for cables within    a fuse facility;-   (b) fastening the thermal element to at least one of the fuse    elements in the fuse facility or to cables in a vicinity of where    they are coupled to their respective fuse elements; and-   (c) coupling the thermal element to a fire preventing unit which is    operable to raise an alarm when a temperature measured in use by the    thermal element exceeds a temperature threshold.

Details of the invention can be combined in other combinations whilstremaining within the scope of the present invention as defined by theappended claim set.

DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by examples,with reference to the drawings wherein:

FIG. 1 is a schematic illustration of an electrical system whichcomprises a fuse cabinet with fire warning pursuant to an embodiment ofthe present invention;

FIG. 2 is a schematic illustration of an example of a manner in which athermal element implemented as a string which is fastened to a number offuses in the fuse cabinet illustrated in FIG. 1;

FIG. 3 is an alternative schematic illustration of the thermal elementof FIG. 2 attached to fuses in the fuse cabinet;

FIG. 4 is a schematic illustration of a lockable clamp in side view forimplementing the invention;

FIG. 5 is an illustration of details of a lock house of the lockableclamp shown in FIG. 4;

FIG. 6 is an illustration of a part of a leg from the lockable clamp ofFIG. 4;

FIG. 7 is an illustration of an alternative implementation of theinvention as shown in FIG. 1 with a thermal element plaited in betweencurrent cables and maintained in position with adhesive or similar;

FIG. 8 is an illustration of a further alternative implementation of theinvention as shown in FIG. 1, wherein the thermal element is laid ontocurrent cables and held in position by using clamping components;

FIG. 9 is an illustration of a clamping component of FIG. 8 as seen fromvarious angles; and

FIG. 10 is an illustration of a further alternative implementation ofthe invention as shown in FIG. 1, wherein the thermal element is laidonto the current cables and maintained in position by use ofpress-fastening components, for example known as “Velro strip” asdescribed in a U.S. Pat. No. 4,531,634 which is hereby incorporated byreference.

In the accompanying diagrams, an underlined number is inserted torepresent an element over which the underlined number is placed or anelement adjacent to the underlined number. A non-underlined numberrelated to an element is identified by a line between the non-underlinednumber and the element. When a number if not underlined and isaccompanied by an associated arrow, the non-underlined number is used toidentify a general element towards which the arrow is pointing.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

An aim of the present invention is to ensure improved security againstfires in electrical systems.

In FIG. 1, there is shown an electrical system indicated generally by 10which comprises a fuse cabinet 20. The fuse cabinet 20 comprises aplurality of fuse elements 30 which are provided with electrical powervia electrical cables 40. The fuse elements 30 are implemented in tworows. The cables 40 are coupled to a metering instrument 200 asillustrated. The metering instrument 200 measures the electricityconsumption via the system 10. A thermal element 50 comprises astretched out thermal element string or flat band which is laid in loopswithin the fuse cabinet 20 itself, up and around and in close contactwith all elements which unintentionally can be expected to developwarmth when they are in operation, for example the fuse elements 30 andthe electrical cables 40.

The thermal element string is beneficially arranged in a non-conductivesleeve which is able to withstand relatively high temperaturesapproaching 200° C. or higher; for example, the sleeve can be fabricatedby employing woven fibreglass with silicone rubber and/or PVC. FIG. 1 isa schematic illustration of the string arrangement onto each fuseelement 30. The string arrangement can be implemented in severaldifferent ways on each fuse element 30 as will be described in detailbelow. FIG. 2 is an illustration of a manner in which the thermalelement 50 can form a contact with both the upper side and underside ofthe fuse element 30. The measuring instrument 200 is coupled via cables170 to an earth fault breaker 140 and thereafter via cables 160 to amain fuse or input fuse 150 to the electrical power supply network. Atleast one of the cables 160, 170 is measured by the thermal element 50as illustrated in FIG. 1. The system 10 comprises further a temperaturemeasuring apparatus 60 coupled to the thermal element 50. Thetemperature measuring apparatus 60 includes an acoustic alarm 70, anoptical alarm 80 and a temperature indicator 90. When the temperaturemeasured by the measuring instrument 60 via the thermal element 50 inoperation exceeds a first temperature threshold, an alarm is activated,for example via the indicator 80 and/or the indicator 90. Beneficially,the measuring apparatus 60 includes an information portal 100, forexample an interface such as an Internet coupling and/or a wirelesscoupling, for providing external warning of fire and/or temperatureincrease.

The thermal element 50 is beneficially implemented as a flat flexiblestrip (a band) which includes at least one of: thermosensitiveresistors, thermocouples, thermal switches (miniature bi-metallicswitches), silicon temperature sensors integrated circuits and similarwhich are operable to generate a signal representative of temperature ofthe fuse elements 30. Such thermal elements are produced, for example byMinco Products Inc., Minneapolis, USA; there are several suppliers ofsimilar types of thermal elements 50.

When a fault occurs in the electrical system 10 which develops warmth,this will very quickly be measured via the thermal element 50 which iscoupled to the measuring instrument 60 which registers changes inpotential in manner which is usual for thermal elements. A change intemperature will change potential in the thermal element 50 which themeasuring instrument 60 interprets to be a fault condition.Alternatively, warning devices 70, 80 can be activated in a faultsituation, namely when a measured temperature exceeds a temperaturethreshold.

A change in warmth at a point along the thermal element 50, thepotential in the circuit of the thermal element 50 changes and willcause an earth failure via the earth circuit breaker 140. The change Inpotential is registered in the fire warning unit 60 which is coupled toearth 110 via a conductor 120, and at the same time coupled to thecircuit breaker 140 and an earth conductor 130. This results in theelectrical supply being switched out. The earth circuit breaker 140 iscoupled to the meter 200 via conductors 170. The conductors 170 arefurther directed to the fuses 30. Tre-phases in the system 10 from themain fuse 150 to the fuses 30 are indicated. Alternatively, the system10 is flexible and can also be used for a 1-phase implementation. Theaforementioned system 10 is implemented such that the system 10decouples the electrical supply in an event that the temperature at eachmeasuring point of the thermal element 50, or within the cabinetgenerally, exceeds a temperature threshold, for example +70° C.

The fire protecting unit 60 can beneficially provide a local alarmwarning, such as by way of the acoustic alarm 70 from a loudspeakerand/or by way of the visual alarm 80, for example a flashing light toshow an alarm situation. In an embodiment of the fire alarm unit mayinclude the temperature indicator 90 which in operation shows thetemperature measured by the thermal element 50. As named above, the firewarning unit 60 includes a portal 100 for providing external warning,for example via a NC-contact, wherein it is possible to couple an alarmcentre or other type of receiver; “NC” is an abbreviation for “normallyclosed”. The coupling and warning is beneficially implemented withoutpotential difference, thereby being independent of provision ofelectrical supply. It is also envisaged that the fire warning unit 60optionally has an integrated transmitter which is operable to send aShort Message System (SMS) message to the user's mobile telephone.

In a preferred embodiment, an even more optimal fire protection isachieved by combining the thermal element 50 in the fuse cabinet 20 witha gas and/or smoke detector 180 which is coupled to the fire alarm unit60 via a wire 190. The smoke- and gas-detector 180, as shown in FIG. 1,disposed uppermost in the fuse cabinet 20, can comprise opticaldetectors, ion detectors or similar with beneficially high sensitivityfor smoke and gases, and which in addition can be pre-calibrated. Thedetectors 180 are operable to detect smoke and/or gas, such as chlorinegas which is expelled from apparatus and cables when heat is generatedand/or fire as a consequence of overload, short circuits, electricalarcs and similar and to send a signal via the wire 190 to the fire alarmunit 60 which can both put in progress external warning and interruptelectrical supply.

In FIG. 2, there is shown in greater detail a manner in which thethermal element 50 is installed, for example, in a loop along forexample thee fuses 30A, 30B, 30C in the cabinet 20. It is a significantdetail that the thermal element 50 forms a tightelectrically-non-conductive thermal contact with the fuse elements 30.For example, it often arises that warmth and corresponding fire iscaused by poor electrical contact between an electrical wire conductorand a screw in a contact block in the fuse 30 and/or corrosion at suchelectrical contact. For example, screws which fasten electric wires,which can loosen in use as a consequence of vibration over a longerperiod of use and associated poor electrical contact, often result infire. As shown in FIG. 2, the thermal element 50 can be installed andclamped to both underside and upper side 260 of fuse elements 30.

In FIG. 3, there is shown a manner in which the thermal element 50 isclamped in use both down towards the upper side and up towards theunderside of the fuse element 30, namely the fuse arrangement. Thethermal element 50 is clamped firmly with good thermal contact by use ofa fastening clamp indicted generally by 300 pursuant to the presentinvention. The fastening clamp 300 is shown as a U-shaped bracket whichis fastened in over the fuse element 30, such that it is clamped in ontoan underside and upper side of the fuse element 30. Moreover, thefastening clamp 300 comprises a locking arrangement 320 which makes itpossible to adjust the fastening clamp 300 for adapting it to varioussized of the fuse elements 30 and also rendering it possible for thethermal element 50 is retained securely in position.

In FIG. 4 to FIG. 6, there is shown a more detailed implementation ofthe clamping element 300. The clamping element 300 comprises first andsecond L-formed bracket parts 310A, 310B respectively. The bracket parts310A, 310B are assembled together in use such that the two provideparallel clamping leg parts equipped with soft rubber- and/orfelt-sockets or sleeves 330 for providing a clamping effect against thefuse element 30 above and below as shown in FIG. 2 and FIG. 3. TheL-form bracket parts 310A, 310B and their soft rubber socks or sleeves320 can be moved towards and away from one another, namely they aremoveable to a clamping position when drawn together, and to a loosenedposition when moved away from one another.

In order to reduce costs during manufacture, the bracket parts arebeneficially manufactured from a hard plastics material, namely from aglass-filled plastics material. In order to provide a soft clampingeffect from the clamp leg parts over the thermal element 50 which shalllie onto the fuse elements 30, each of them is furnished with a sleeve350 of soft rubber and/or felt. Thereby crushing damage of the thermalelement 50 is avoided.

The ends of the bracket parts 310A, 310B are implemented to be attachedtogether by passing through the lock house 320 which includes a lockingarrangement 380 such that these parts can be attached to one another. Asillustrated in FIG. 5, the lock house 320 is fixed and fastened to oneof the long leg parts 310A, 310B whereas the other part runs adjustablythrough the lock house 320. The locking arrangement 380 comprises a lockplate which can be used to clamp the leg parts 310A, 310B together asshown in FIG. 5 to FIG. 6. There is used a lock tag 400 fastened to oneof the leg parts 310A, 310B as shown for avoiding that the leg parts310A, 310B loosen after installation, for example as a consequence ofvibration for longer periods of times.

It is the intention that the thermal element 50 is permanently mountedto the fuse elements 30 in the cabinet 20. Moreover, with the lockingmechanism according to the present invention, the thermal element 50,over the whole or over portions of its extent through the fuse elements30, can be relatively easily loosened, in an event that it is necessaryto change its path over the electrical contacts of the fuse elements 30which are to be monitored pursuant to the present invention. There canarise a need to move or temporarily remove the thermal element 50, in anevent that there is further construction work or repairs within thecabinet 20. The present invention is especially well suited for use infuse cabinets, especially in domestic installations, to avoid dangerousevolvement of heat which can potentially give rise to fires.

The invention is advantageously adapted for early detection of faultspoint in fuse cabinets and thereby better ensure that the whole fusecabinet or individual components in the fuse cabinet are decoupled fromthe electrical supply network before fire can occur. The fasteningarrangement shown in FIG. 3 to FIG. 6 enables rapid installation of thesystem 10. In the present invention, there is employed a technology byway of the use of the thermal element, for example “thermocouple”,thermistor or similar. “Thermocouples” are based on two different metalsinducing a potential difference when they are coupled together. Thepotential difference is moreover dependent upon warmth, namelytemperature differences, in that one can compute the temperaturedifference from the induced potential. One or more conductors of thethermal element 50 which are operable to measure temperature is wound orplaited along all relevant electrical conductors which carry electricalcurrent, and also switches and other relevant components which canpotentially represent an origin for fire. All components in the fusecabinet can be protected by way of the same lengthily deployed thermalelement pursuant to the present invention.

In an embodiment of the invention, each individual component and/orindividual circuit coupled individually through the thermal element 50.The benefit of this configuration with a divided fuse element 30 asshown in FIG. 1 is that not the whole of the fuse cabinet 20 must bedisconnected from the electrical supply network when warmth is developedin a cable and/or circuit in the cabinet 20. Instead, it is possible todisconnect individual circuits and/or units of grouped components and/orcircuits. Moreover, it can assist to identify elements and/or unitswhere there faults have arisen in the form of the development of warmth.For example, the thermal element 50 can optionally include a row ofthermal sensors along its length, and the fire warning unit 60 isbeneficially provided with individual signals from each one of thethermal sensors. This makes it possible to identify immediately one ormore specific fuse elements 30 whereat a fault has arisen. For example,the thermal element 50 is equipped with silicon integrated circuitswhich scan and multiplex temperature measurements from the thermalsensors included along the thermal element 50, to send a compositemultiplexed signal to the fire alarm unit 60 representative of thetemperature of the fuse elements 30.

When a malfunction occurs in electrical equipment in the cabinet 20,which develops warmth, this will be very rapidly detected by the thermalelement 50. A change in temperature will change the induced potential inthe circuit of the thermal element 50, and there can be implementedtherefrom a break in the electrical supply via creating an Earthingfault.

When a fault is detected, the whole fuse cabinet 20, or one or moreunits and/or circuits are disconnected from the electrical supplynetwork. In an alternative embodiment of the invention severalco-located cabinets are simultaneously disconnected from the electricalsupply network when a development of warmth, smoke and/or gas isdetected in one or more of the cabinets 20.

Isolation of electrical supply from the cabinet 20 or individualcomponents, units and/or circuit in the fuse cabinet 20 beneficiallyoccurs by generating an Earthing fault by coupling out the Earth faultbreaker 140. Alternatively, or in addition, there can be included aprotection which is operable to disconnect the mains electrical supply,beneficially implemented via a relay switch and/or an over voltagebreaker which interrupts power supply.

In a preferable embodiment a yet more optimal fire protection isachieved by combining temperature measurement in the fuse cabinet 20with gas- and/or smoke detector in the fuse cabinet 20. This will givean additional safety when the thermal element 50 for one or anotherreason fails to function. Smoke- and/or gas measurement devices arebeneficially included in the upper part or in the top of the fusecabinet 20. Such smoke- and/or gas sensor are for example implemented asone or more optical detectors, ion detectors, electrochemical detectorsad similar. The detectors will be able the detect smoke and/or gas suchas, for example, chlorine gas which is generated from apparatus andcables when they melt and/or begin to burn, for example as a consequenceof overload, short circuit, electrical arcs and similar.

In an advantageous embodiment the fire warning unit 60 is coupled to aphysically remote external receiver, for example via a numbertransmitter which warns via a short message system (SMS) a user equippedwith a mobile telephone. In another advantageous embodiment of theinvention, a signal is sent to a coupled fire alarm centre, a combinedfire- and burglary-alarm system, other form of alarm monitoring centre.Beneficially, a warning is generated without potential and without aneed for electrical supply, for example telecommunication of varioustypes. In a beneficial embodiment of the invention, the fire alarm unithas a NC-switch (namely “normally closed”) for potential-free alarmcoupling.

The fire alarm unit 60 can optionally have a temperature indicator asaforementioned which shows temperature measured by the thermal element50 and/or a thermometer localized in a suitable location within thecabinet 20. Thereby a user can see where high temperature events occur.Moreover, this can be used for identifying a risk of danger inindividual circuits, especially when these are coupled to the fire alarmunit 60 via one or more separate thermal elements 50 and by measuringthe temperature and is shown separately for each unit and/or circuit.

Fire situations often arises as a consequence of development of warmthwhere cables are clamped, for example at screws, in fuses, for exampleon account of a screw loosening by vibration or on account of corrosionover time. The tendency is that one of the cables 510 is clamped intothe fuse 30 and is warmed up and that insulation begins to melt andcatch fire. In order to best measure such a development of warmth, thethermal element 50 is mounted to the fuse elements 30 as illustrated inFIG. 7 in a plaited manner as indicated generally by 500. The thermalelement 50 can have a length in a range of 10 cm to 10 metres,especially in a range of 0.5 metres to 5 metres. The thermal element 50beneficially has a width in a range of 5 mm to 5 cm, more beneficiallyit has a width of 1 cm. Moreover, the thermal element 50 beneficiallyhas a thickness in a range of 0.5 mm to 3 mm, and advantageouslysubstantially 1 mm thickness. Beneficially, the thermal element 50 isflat as shown in FIG. 7 and is protected by a sleeve fabricated fromnon-combustible electrically-isolating material, for example glass fibrestrengthened with silicone rubber. Optionally, after installation, glue520 is employed for holding the thermal element 50 securely in placeabutting onto the cables 510 where joined to the fuse elements 30 asillustrated in FIG. 10. The thermal element 50 can optionally beinstalled either before or after coupling the cables 510 to the fuseelements 30.

In some situations, for example when the cables 510 are alreadyinstalled and coupled to the fuse elements 30 and when the thermalelement 50 is relatively long, for example 5 metres, it is advantageousto use fasteners 580 for fastening the thermal element 50 against oneside of the cables 510 as shown in FIG. 8 in order to avoid a need toplait the thermal element 50. Optionally, at least one side of thethermal element 50 provided with adhesive such that the thermal element50 can be pressed into position onto the cables 510 and so thereafterfastened into position by using the fasteners 580 which can be slid upalong the cables 510 and finally pushed up to fasten to both the cables510 and the thermal element 50. The fasteners 580 can either beinstalled individually, or can be implemented as a series of fasteners580 injection moulded as a component for enabling a yet more rapidinstallation to be achieved.

In FIG. 9, the fastener 580 is illustrated in more detail. The fastener580 is beneficially an injection moulded component fabricated fromflexible glass-filled plastics material which imparts it with lowflammability. Alternatively, the fastener 580 can be fabricated from aflexible metal which is moulded within a layer of plastics material suchas silicone. The fastener 580 comprises two fastening legs 600A, 600Bwith a projection 610 which can effectively be fastened to the thermalelement 50. Moreover, the fastener 580 includes a back portion 620 witha depression 630 for receiving the cable 510. In use, the fastener 580is brought into contact with an outer insulation of the cable 510 and issubsequently slid along the 510 until the fastening legs 600A, 600B makecontact with the thermal element 50 and holds it pressed against thedepression 630 in the back portion 620. The depression 630 and the backportion 620 are beneficially formed with surface roughness for improvingfastening action. In order to implement the invention, several fasteners580 together with one of more thermal elements 50 are included in anapparatus, a so-called “kit of parts”. The embodiment of the inventionas illustrated in FIG. 9 is especially advantageous on account of itbeing susceptible to rapid installation, such that a cost of timerequired for installation can be reduced.

In order to make possible more rapid installation of the thermal element50 to the cables 510 in the fuse cabinet 20, an arrangement as indicatedby 700 in FIG. 10 can be used. The thermal element 50 is equipped on itsunderside which contacts onto the insulation of the cable 510 with acoupling arrangement implemented with miniature press-activated couplingprojections, for example in a manner known as “Velcro strip” asdescribed in U.S. Pat. No. 4,531,634 which is herewith referred to.“Velcro” is a registered trademark. During installation, these miniaturecoupling projections is optionally clipped away or removed byinstallation personnel for achieving an improved thermal contact betweenthe thermal element 50 and insulation of the cables 510. Thereafter, aback coupling strip 710 is pressed up onto the underside of the thermalelement 50 for maintaining the thermal element 50 in position on thecables 510. Optionally, some adhesive can be smeared onto the cables 510before the thermal element 50 is placed in position for providing aneven more secure mounting of the thermal element 50 onto the cables 510.Alternatively, the coupling strip 710 is cut to a suitable length withscissors, depending upon design and location of the fuse cabinet 20.

The invention as herewith described and defined in the accompanyingclaim set can be implemented in many different manners. For example,private persons can themselves install the safety system in their homesby using apparatus as aforementioned (“kit of parts”) pursuant to thepresent invention which includes all components for implementing theinvention.

When an installation engineer employs the invention for a customer inreturn for payment, the method of implementing the invention is alsopossible to protect using patent rights. Moreover, components adaptedfor implementing the invention can also be protected via patent rights.Moreover, the thermal element is specially adapted for implementing theinvention, something which can also be protected via patent rights.

The invention can be modified by way of embodiments without deviatingfrom the scope of the invention as defined in the accompanying claims.Features of the present invention as described in the foregoing aresusceptible to being combined in any combination whilst remaining withinthe scope of the present invention.

Phrases such as “including”, “comprising”, “incorporating”, “consistingof”, “have”, “are” used for describing the invention are intended to beconstrued in a non-limiting manner, namely such that for elements,components or elements which a not explicitly described can also bepresent. Reference to the singular is also to be construed to be areference to the plural.

Numbers included within parentheses in the appended claim are intendedto assist understanding of the claims and should not be used in any wayto limit the scope of protection defined by the claims.

1. An apparatus (30, 50, 60) for providing fire protection in anelectrical system (10) at coupling points of cables (510), characterizedin that the apparatus (50, 60) comprises at least one thermal element(50) which is operable to detect and warn of increased warmth in theelectrical cables (510), one or more electrical elements (30) where thecables (510) are coupled, and a fire warning unit (60) coupled inoperation to said at least one thermal element (50) for sending warningin an event that the thermal element (50) measures a temperature riseabove a temperature threshold.
 2. An apparatus (30, 50, 60) as claimedin claim 1, wherein the thermal element (50) is implemented as anelongate ribbon/band which can be coupled in series along the couplingpoints for simultaneously monitoring a plurality of coupling points. 3.An apparatus (30, 50, 60) as claimed in claim 2, wherein the thermalelement (50) has a length in a range of 10 cm to 10 metres.
 4. Anapparatus (30, 50, 60) as claimed in claim 2 or 3, wherein the thermalelement (50) is installed in a region where the cables (510) are coupledto said one or more electrical elements (30) for detecting warming ininsulating material of the cables (510) adjacent to where the cables(510) are coupled.
 5. An apparatus (30, 50,60) as claimed in claim 1, 2,3 or 4, wherein the thermal element (50) comprises at least twodifferent metals which in use induce an electro-thermal potential whencoupled together, and which exhibit a change in potential when subjectto a temperature change in use.
 6. An apparatus (30, 50, 60) as claimedin one of the preceding claims, wherein the thermal element (50) isequipped with a sleeve or sock as outer protection, and wherein thesleeve or sock is adapted to give an electrically insulating thermalcontact with said coupling points in the electrical system (10).
 7. Anapparatus (30, 50, 60) as claimed in any one of the preceding claims,wherein one or more fasteners (300, 520, 580, 710) are employed toestablish contact between the thermal element (50) and the cables (510),and wherein said one or more fasteners (300, 520, 580, 710) press ormaintain the thermal element (50) abutting onto the coupling points. 8.A fastener (300, 520, 580, 710) for coupling a thermal element (50) ofan apparatus (30, 50, 60) as claimed in any one of the preceding claims.9. A fastener (300, 520, 580, 710) as claimed in claim 8, wherein saidfastener (300) includes a bracket adapted to provide a loosenableclamping of the thermal element (50) to one or more of the couplingpoints.
 10. A fastener (300) as claimed in claim 9, wherein the bracketcomprises two L-form bracket parts which are restricted in motion in alocked position and have a freely adjustable position, and thereby formtwo clamping parts adapted to form a clamping contact to one or more ofthe coupling points.
 11. A fastener (300) as claimed in claim 10,wherein the bracket parts include main portions which are adapted to becoupled together via a locking arrangement adapted to provide saidlocked position for the brackets.
 12. A fastener (520) as claimed inclaim 8 which is slidable along the cables (510) and to at least a partof the thermal element (50) for fastening the thermal element (50) tothe cables (510) in a vicinity of their coupling points.
 13. Akit-of-parts for making it possible to install an apparatus (30, 50, 60)as claimed in any one of claims 1 to
 6. 14. A kit-of-parts as claimed inclaim 13, wherein the kit-of-parts comprises one or more fasteners asclaimed in any one of claims 8 to
 12. 15. A method of installing anapparatus as claimed in any one of claims 1 to 6, wherein the methodincludes: (a) laying a thermal element (50) along coupling points forcables (510) in a fuse facility (20); (b) fastening the thermal element(50) to at least one of the fuses (30) in the fuse facility (20) or tocables (510) in a vicinity of where they are coupled to their respectivefuse elements (30); and (c) coupling the thermal element (50) to a firewarning unit (60) which is adapted to provide an alarm when atemperature measured in operation by the thermal element (50) exceeds atemperature threshold.